The objectives of this proposal are to determine the serum levels of protein SAA in neoplastic diseases, relate these data to diagnosis and prognosis and define the relationship of this protein to the immune dysfunctions noted in cancer. This protein (SAA) which is the precursor of secondary amyloid is present in all normal sera and has been shown to be increased in a number of acute and chronic diseases as well as in cancer. SAA in the murine model of secondary amyloidosis has previously been shown to suppress the formation of antibody in in vitro cultures of splenic lymphocytes. SAA levels will be determined by radioimmunoassay using radiolabeled amyloid protein AA and antiserum specific for AA. Sera will be collected from patients with cancer of lung, bowel, breast and lymphoma at the time of initial diagnosis and at periodic intervals thereafter. SAA levels will be correlated with type of tumor, response to therapy, and presence or absence of recurrent tumor. A relationship between SAA levels and lymphocyte dysfunction as measured by mitogen stimulation and T and B cell enumeration will be sought. The effect of SAA on the in citro formation of antibody by human lymphocytes will be evaluated using a modification of the Marbrook culture technique with SRBC as antigen and response will be measured by the hemolytic plaque assay. Purified human SAA will be used for these experiments to avoid other suppressors of the immune system which may be present in cancer serum. The objective of these experiments is to show whether SAA can cause suppression of the immune response in the human as well as in the murine system.